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/*******************************************************************************
* Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
*******************************************************************************
*/
#include "rtc_api.h"
#include "cmsis.h"
#include "rtc_regs.h"
#include "pwrseq_regs.h"
#include "clkman_regs.h"
static int rtc_inited = 0;
static volatile uint32_t overflow_cnt = 0;
static uint32_t overflow_alarm = 0;
//******************************************************************************
static void overflow_handler(void)
{
MXC_RTCTMR->flags = MXC_F_RTC_FLAGS_ASYNC_CLR_FLAGS;
overflow_cnt++;
if (overflow_cnt == overflow_alarm) {
// Enable the comparator interrupt for the alarm
MXC_RTCTMR->inten |= MXC_F_RTC_INTEN_COMP0;
}
}
//******************************************************************************
static void alarm_handler(void)
{
MXC_RTCTMR->inten &= ~MXC_F_RTC_INTEN_COMP0;
MXC_RTCTMR->flags = MXC_F_RTC_FLAGS_ASYNC_CLR_FLAGS;
}
//******************************************************************************
void rtc_init(void)
{
if(rtc_inited) {
return;
}
rtc_inited = 1;
// Enable the clock to the synchronizer
MXC_CLKMAN->clk_ctrl_13_rtc_int_sync = MXC_E_CLKMAN_CLK_SCALE_ENABLED;
// Enable the clock to the RTC
MXC_PWRSEQ->reg0 |= MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN;
// Set the divider from the 4kHz clock
MXC_RTCTMR->prescale = MXC_E_RTC_PRESCALE_DIV_2_0;
// Enable the overflow interrupt
MXC_RTCTMR->inten |= MXC_F_RTC_FLAGS_OVERFLOW;
// Prepare interrupt handlers
NVIC_SetVector(RTC0_IRQn, (uint32_t)alarm_handler);
NVIC_EnableIRQ(RTC0_IRQn);
NVIC_SetVector(RTC3_IRQn, (uint32_t)overflow_handler);
NVIC_EnableIRQ(RTC3_IRQn);
// Enable the RTC
MXC_RTCTMR->ctrl |= MXC_F_RTC_CTRL_ENABLE;
}
//******************************************************************************
void rtc_free(void)
{
if (MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_ENABLE) {
// Clear and disable RTC
MXC_RTCTMR->ctrl |= MXC_F_RTC_CTRL_CLEAR;
MXC_RTCTMR->ctrl &= ~MXC_F_RTC_CTRL_ENABLE;
// Wait for pending transactions
while(MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_PENDING);
}
// Disable the clock to the RTC
MXC_PWRSEQ->reg0 &= ~(MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN | MXC_F_PWRSEQ_REG0_PWR_RTCEN_SLP);
// Disable the clock to the synchronizer
MXC_CLKMAN->clk_ctrl_13_rtc_int_sync = MXC_E_CLKMAN_CLK_SCALE_DISABLED;
}
//******************************************************************************
int rtc_isenabled(void)
{
return (MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_ENABLE);
}
//******************************************************************************
time_t rtc_read(void)
{
unsigned int shift_amt;
uint32_t ovf_cnt_1, ovf_cnt_2, timer_cnt;
// Account for a change in the default prescaler
shift_amt = MXC_E_RTC_PRESCALE_DIV_2_12 - MXC_RTCTMR->prescale;
// Ensure coherency between overflow_cnt and timer
do {
ovf_cnt_1 = overflow_cnt;
timer_cnt = MXC_RTCTMR->timer;
ovf_cnt_2 = overflow_cnt;
} while (ovf_cnt_1 != ovf_cnt_2);
return (timer_cnt >> shift_amt) + (ovf_cnt_1 << (32 - shift_amt));
}
//******************************************************************************
uint64_t rtc_read_us(void)
{
unsigned int shift_amt;
uint32_t ovf_cnt_1, ovf_cnt_2, timer_cnt;
uint64_t currentUs;
// Account for a change in the default prescaler
shift_amt = MXC_E_RTC_PRESCALE_DIV_2_12 - MXC_RTCTMR->prescale;
// Ensure coherency between overflow_cnt and timer
do {
ovf_cnt_1 = overflow_cnt;
timer_cnt = MXC_RTCTMR->timer;
ovf_cnt_2 = overflow_cnt;
} while (ovf_cnt_1 != ovf_cnt_2);
currentUs = (((uint64_t)timer_cnt * 1000000) >> shift_amt) + (((uint64_t)ovf_cnt_1 * 1000000) << (32 - shift_amt));
return currentUs;
}
//******************************************************************************
void rtc_write(time_t t)
{
// Account for a change in the default prescaler
unsigned int shift_amt = MXC_E_RTC_PRESCALE_DIV_2_12 - MXC_RTCTMR->prescale;
MXC_RTCTMR->ctrl &= ~MXC_F_RTC_CTRL_ENABLE; // disable the timer while updating
MXC_RTCTMR->timer = t << shift_amt;
overflow_cnt = t >> (32 - shift_amt);
MXC_RTCTMR->ctrl |= MXC_F_RTC_CTRL_ENABLE; // enable the timer while updating
}
//******************************************************************************
void rtc_set_wakeup(uint64_t wakeupUs)
{
// Account for a change in the default prescaler
unsigned int shift_amt = MXC_E_RTC_PRESCALE_DIV_2_12 - MXC_RTCTMR->prescale;
// Disable the alarm while it is prepared
MXC_RTCTMR->inten &= ~MXC_F_RTC_INTEN_COMP0;
MXC_RTCTMR->flags = MXC_F_RTC_FLAGS_COMP0; // clear interrupt
overflow_alarm = (wakeupUs >> (32 - shift_amt)) / 1000000;
if (overflow_alarm == overflow_cnt) {
MXC_RTCTMR->comp[0] = (wakeupUs << shift_amt) / 1000000;
MXC_RTCTMR->inten |= MXC_F_RTC_INTEN_COMP0;
}
// Enable wakeup from RTC
MXC_PWRSEQ->msk_flags &= ~(MXC_F_PWRSEQ_MSK_FLAGS_RTC_ROLLOVER | MXC_F_PWRSEQ_MSK_FLAGS_RTC_CMPR0);
}
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